1. Field of the Invention
The present invention relates to a manufacturing method of light-emitting diode, more specifically to a manufacturing method of a light-emitting diode in which a light-emitting diode element is mounted on a substrate.
2. Description of the Related Art
In recent years, there is developed a white light source comprising a blue light-emitting diode element and a fluorescent material that is excited by a portion of blue light emitted from the blue light-emitting diode element, and, as a result, a conventional light source in lighting, automobile lamps, TVs and personal computers is being rapidly replaced by a light-emitting diode (hereinafter referred to as “LED”). Various methods of manufacturing the LED used in these lighting fixtures and electrical appliances are proposed.
As a conventional manufacturing method of LED in which the LED elements are mounted, there is disclosed a manufacturing method in which the LED elements are mounted one by one on a substrate assembly (refer, for example, to pages 6-7 and FIGS. 2-3 of Japanese Unexamined Patent Application Publication No. 2008-521210). This conventional manufacturing method of LED is now described simply on the basis of FIG. 4.
As shown in FIG. 4A, a substrate assembly 51 includes an upper surface 51a provided with a plurality of pairs of upper surface electrodes 52, and a lower surface 51b provided with a plurality of pairs of lower surface electrodes 56. The pairs of upper surface electrodes 52 and the pairs of lower surface electrodes 56 are electrically connected, respectively, by via conductors or through-holes 57 provided inside the substrate assembly 51, and pairs of bumps 53 are respectively formed on the pairs of upper surface electrodes 52.
Next, LED elements 54 are mounted individually on the pairs of bumps 53, as shown in FIG. 4B. Then, as shown in FIG. 4C, a phosphor resin portion 55 is formed on the upper surface of the substrate assembly 56 to cover a plurality of the LED elements 54 that are mounted on each of the pairs of bumps 53 on the substrate assembly 58, and the LED elements and an entire upper surface of the substrate 58 are sealed. Then, subsequent to polishing an upper surface of the phosphor resin portion 55, the phosphor resin portion 55 and the substrate 58 are simultaneously cut using a rotary blade 59, as shown in FIG. 4D, to divide into a plurality of separated LEDs 50, as shown in FIG. 4E.
Meanwhile, as a conventional technology for a manufacturing method of LED with electrode plates formed on opposite sides of LED element to emit light from an end surface (side surface) of the LED, there is disclosed a manufacturing method that directly involves manufacturing processes to divide into a plurality of LED elements diced on an expanding tape (refer, for example, to pages 4-5 and FIGS. 1-8 of Japanese Unexamined Patent Application Publication No. 10-144631). This conventional manufacturing method is now described simply on the basis of FIG. 5.
A lower surface of an LED epitaxial wafer (hereafter referred to as “LED wafer”) 1 is attached to a dicing sheet 2, as shown in FIG. 5A, the LED wafer 1 having a pair of element electrodes of anode and cathode, with one of the anode and the cathode formed at an upper surface, and the other of the anode and the cathode formed at a lower surface of the LED wafer 1. Subsequently, as shown in FIG. 5B, the LED wafer 1 is full-cut diced longitudinally and laterally to a desired element size, thereby forming a plurality of LED elements 4 on the dicing sheet 2. Next, as shown in FIG. 5C, the dicing sheet 2 is expanded to a certain size thereby enlarging a space between one another of the LED elements 4, and, as shown in FIG. 5D, an electrode plate 5 is attached by an anisotropically conductive adhesive 6 to the upper surfaces with element electrodes 4a that is one of the anode and the cathode of the LED elements 4.
Next, subsequent to removing the dicing sheet 2 from the LED elements 4, an electrode plate 7 is attached by the anisotropically conductive adhesive 6 to the lower surfaces with element electrodes 4b that is the other of the anode and cathode of the LED elements 4, as shown in FIG. 5E. In addition, as shown in FIG. 5F, a light-transmitting insulator 9 is injected to fill between each of the LED elements 4, and, as shown in FIG. 5G, parts where the electrode plates 5 and 7 and the light-transmitting insulator 9 are positioned are full-cut diced in one direction to divide into a plurality of LEDs 10.
However, in the above-described manufacturing method of LED 10 with electrode plates formed on opposite sides of LED element, a pair of electrode plates 5 and 7 are respectively formed at places that become the upper and lower surfaces (or right and left surfaces) of the individual LED elements, followed by separation into small pieces for supply. Moreover, pulling an outer periphery of the expanding tape is used just to widen the space between the individual elements from the state where the LED wafer 1 is cut into the plurality of LED elements 4 on the expanding tape. There is thus a problem that, although dicing into individual LED elements 4 allows the plurality of LED elements 4 having the pair of electrode plates formed on the upper and lower surfaces (or right and left surfaces) to be obtained, the LED elements 4 are then mounted one by one on substrates, and it requires a high degree of precision to individually place the respective electrode plates of the LED elements 4 on electrodes of the substrate, leading to an increase in mounting time.